This invention relates generally to the art of non-impact printing, and more particularly to advancing mechanisms for a web of recording medium for ink jet printing.
An asynchronous volume displacement droplet ejection type of ink jet head is described in U.S. Pat. No. 3,946,398 - Kyser et al (1976) and co-pending patent application Ser. No. 489,985, filed July 19, 1974, both assigned to the assignee of the present application. A piezoelectric element is associated with an ink jet chamber, resulting in ejecting a droplet of ink from a nozzle of the chamber with sufficient velocity for it to travel to a recording medium. One such droplet forms a portion of a character to be printed. A plurality, such as seven or nine, print heads of this type are preferably built as a single structure that is mechanically swept across a recording medium upon which the printing is taking place line by line. At each column of the printing line the appropriate number of the independently controllable ink jet chambers are fired by pulsing their respective piezoelectric elements to eject ink drops therefrom.
Such a mode of printing requires a means for advancing the recording medium after a line of printing has been completed. Previous efforts in this area of non-impact printing are needlessly complex with high power requirements and are not entirely suitable for this method of asynchronous ink jet printing. The present invention, directed toward non-impact printing and particularly toward asynchronous ink jet printing, provides an improved recording medium advancing mechanism for ink jet printing with some unique features.